Traffic controllers are utilized as intimidating devices that preclude traffic of autos and the like at the entrances and exits of parking lots and like facilities. That is, a visible barrier is presented at the pavement level so as to permit the desired traffic flow by means of its retraction, and to prevent unauthorized traffic by means of its raised and visible configuration in the form of a projecting curb or the like of substantial height. The curb configuration is menacing when projecting above the pavement level, and can be the cause of damage to the tires and to the undercarriage of vehicles attempting to encroach over the said barrier curb. The curb configuration of the controller is essentially a barrier that is substantially impassible by wheeled vehicles, and it is rugged massive. Consequently, rapid operation becomes a problem with respect to power requirements related to acceleration and deceleration, when operating the controller from closed to open conditions and vise versa. It is a general object of this invention therefore, to provide economical rapid actuation of a safety barrier of the curb type in a traffic-way controller.
The traffic-way controller as it is disclosed herein is a massive curb that extends from and retracts into the surface of a traffic-way, and it is characterized by a flat surface coplanar with the traffic-way when retracted, and by a sharply inclined surface made thereby when raised or extended. The curb is hinged and in the nature of a hatch door pivoted to a burried frame to be operated from a complementary opening therein. It is an object of this invention to rapidly extend and retract said massive curb by means of a fluid pressure source applied directly between the curb and frame and responsive to a valve control to extend and to retract the curb. In its basic form the fluid pressure source is applied directly from a demand motor driven pump means and directed by a four-way two position valve means to opposite ends of a double acting cylinder and piston means so as to extend and retract the curb as required. In another form, the fluid pressure source is applied directly from a continuously operated motor driven pump means and directed by a four-way three position valve means to opposite ends of a double acting cylinder and piston means, with a center by-pass condition for free flow when the curb is either extended or retracted. With the demand and continuous motor driven pump concepts the velocity of curb movement between the extended and retracted positions is dependent entirely upon the power of the motor and pump capacity, a limiting factor when economizing in the selection of these pressure source components. Therefore, it is an object of this invention to improve upon the pure kinetic power source and substitute therefor a potential energy pressure source, whereby the power and pumping capacities of the motor and pump components can be substantially reduced and minimized. In the improved form the fluid pressure source is reestablished upon demand as potential energy and at a rate that will meet the demand of normal intermittent operation of the curb barrier.
The actuation of the curb between extended and retracted posititions is by fluid actuation, it being an object to minimize power as well as pump rate requirements. With the present invention, a fluid pressure accumulator is employed, and wherein liquid is stored between predetermined high and low pressure levels, as potential energy. For example, an actual reduction to practice involves cylinder and piston actuators that require nine gallons per minute of liquid volume, with a cycle operation requirement of four and one half movements per minute. Consequently, two gallons per minute pumping rate is all that is required, and in practice this is accomplished up to 1500 p.s.i. with a two horse power motor that operates intermittenly upon demand, dependent upon the frequency of extension and retraction of the curb. A high-low pressure sensor automatically controls operation of the motor-pump means.
It is also an object of this invention to provide for positive movement and positioning of the curb barrier, and to this end there is fluid restriction on the discharge of hydraulic fluid back to a reservoir. Since the hydraulic fluid, liquid, is substantially incompressible the depression forces upon the curb as they may be caused impact are positively checked. However, it is also an object to absorb and dissipate high energy shock or impact pulses, and to this end said restriction and discharge to the reservoir is by a flow restrictor and pressure relief means with a by-pass return to said reservoir. In practice, this flow restrictor is also adjustable for determining the rate of movement imparted to the curb barrier.
The hydraulic safety barrier traffic-way controller of the present invention is electrically controlled by a solenoid actuated valve, and with limit switches and/or UP and DOWN switches, as will be described. With the basic demand flow form of this invention there are limit switches to control the motor-pump means, with UP and DOWN switching to position the direction valve. With the continuously operating motor-pump means embodiment there is UP and DOWN switching with a center dump position of the direction valve. With the improved potential energy embodiment there is simply an UP and DOWN switching, utilizing an inexpensive four-way two position valve, while the pressure source is automatically maintained as a potential to meet the operational demand of cycle frequency.